Several factors can contribute to the development of spinal muscular atrophy, or SMA, a condition that affects the nervous system. These include genetics, age, and environment. Fortunately, there are treatments available to slow the progression of the disease. These treatments may also help relieve symptoms.
Early detection
Earlier detection of spinal muscular atrophy is a good way to avoid rapid loss of motor function and improve the quality of life. Fortunately, effective technology exists for genetic screening. The federal government has added SMA to the Recommended Uniform Screening Panel, a list of conditions that should be screened for during the first year of a child’s life.
The genetics of SMA lend itself to population-based genetic screening. Carriers can be identified through a simple blood test. The results are about 90 percent accurate.
A carrier’s chance of having a child with SMA is one in four. However, if a parent has one nonfunctioning gene, there is a 25% chance that the child will inherit the mutation.
Early detection of SMA can extend a child’s life span and improve their quality of life. Some states have started screening newborns for SMA as part of their newborn screenings. The test can help diagnose SMA and other related nerve and muscle disorders. It also reduces the need for permanent ventilation.
Another test can detect SMA through a polymerase chain reaction (PCR). The PCR can be performed on dried blood samples and will identify the disease in 95% of cases.
The most common genetic defect associated with SMA is a homozygous deletion of the exon 7 of the SMN1 gene. This is the gene that produces the survival motor neuron protein. Without the protein, the motor neurons die and the muscles shrink. Affected individuals may never walk, or they may develop a severe degree of muscle weakness.
There are three main types of SMA: type 1, type 2, and type 3. Most people with type 1 SMA are born with severe muscle weakness and require assistance to walk. On the other hand, those with type 2 are able to walk but display moderate respiratory dysfunction and scoliosis.
There are also less serious forms of SMA. These are less severe and can be treated with medical treatments. The natural history of the disease is changing thanks to new treatments. In addition, the use of genetic testing to find the faulty gene can help parents avoid SMA.
Symptoms
Symptoms of spinal muscular atrophy (SMA) include the gradual loss of muscle strength and control. They may start early in life or develop later. They are caused by a deficiency of the SMN protein.
SMA is a neurological disorder that affects the muscles closest to the neck and chest. It is classified into several different types depending on the severity of the symptoms. Each type has its own life expectancy and prognosis. Generally, type 1 and type 2 SMA are more severe than other forms of the disease.
Babies with SMA may have difficulty sucking and breathing. They may also have skeletal deformities. This can cause a number of medical complications. Eventually, they may have to have surgery to correct the deformities. They can also have trouble eating and losing weight. They may need bracing to prevent their muscles from contracting.
Adults with SMA typically have mild symptoms. They may have tremors, weakness, and twitching. They may also be at risk of respiratory infections. They can be wheelchair-bound. They should be consulted by a healthcare professional in case of any sudden illness.
People with SMA also have an increased chance of having a child with the condition. They carry a gene for SMA in their genes. The amount of SMN gene copies in a family is a good indicator of whether or not a child is at risk of having the condition.
People with SMA usually have at least two copies of the SMN2 gene. These genes produce a small amount of SMN protein. They are also present in some people in as many as eight copies. Having more than one copy of the SMN2 gene leads to less severe SMA symptoms.
In people with SMA, the muscles that control breathing and swallowing are weak. This can result in low energy and the need for a ventilator to help breathe. The muscles that support the spine are also affected, which can interfere with a person’s mobility. They can lead to abnormal spinal curvature. This can affect a person’s body image and position.
The most severe form of SMA is called type 1. This is also known as Werdnig-Hoffman disease. The muscle tone is extremely low at birth. It is rare for an infant to survive longer than six months.
Long-term outlook
Approximately one in every 6,000 babies is born with spinal muscular atrophy (SMA). SMA is a progressive, inherited disorder that affects the muscles used for walking, crawling, and breathing.
In SMA, the motor neurons in the spinal cord do not send signals to the muscles, resulting in a loss of muscle function. The muscles begin to deteriorate, and the affected person will never achieve independent standing or ambulation.
While there is no cure for SMA, treatments are available to improve the quality of life of affected children. These treatments are based on the type of SMA the child has. Some types of SMA are more severe than others, and the severity of the disease varies widely from one form to another.
A genetic test can be used to determine if a child has SMA. In addition, many states test for the disease as part of newborn screenings. It is also possible to test the fluid in the amniotic sac for SMA.
Children with SMA are usually highly intelligent. They often receive physical and occupational therapy to help them manage their condition. Although there are no treatments that can reverse the symptoms of SMA, there are drugs that can increase the production of SMN protein. These medications have been shown to increase strength, feeding, and breathing.
In some cases, people with SMA may not have any symptoms at all. They are unaware that they have the disorder, and their parents are generally unaware that they carry a mutated SMA gene. However, there are genetic tests that can identify changes in the SMN1 gene. These tests are about 95% accurate in detecting an altered gene.
Currently, there are four primary forms of SMA. The forms vary in age of onset and severity of muscle weakness. They include SMA type 0 and SMA type 1. A type 0 SMA is characterized by early death due to respiratory failure. Other symptoms include skeletal abnormalities, twitching, and a lack of tendon reflexes.
Most people with SMA will develop scoliosis. This is because the muscles supporting the spine become weakened and short. Some will also develop joint contractures.
Treatment
Despite its devastating effects, there are treatments available for spinal muscular atrophy. These treatments are intended to slow or stop the disease’s progression and to provide patients with a better quality of life. These treatments are based on the type of SMA a patient has.
For children with type 1 SMA, treatments include respiratory support. This is because respiratory problems can shorten the life of a child with this type of SMA. Other symptoms can include difficulty breathing, trouble feeding, and limited movement.
For children with type 2 SMA, treatment includes physical therapy, assistive devices, and occupational therapy. The severity of a child’s symptoms varies, but the majority of affected children live into adulthood. The most severely affected individuals will have a chronic shortening of their muscles. They may have trouble walking or standing without help.
Children with SMA type 3 are usually diagnosed before age three. Some will experience mild to moderate leg muscle weakness. They may not be able to run or climb stairs. Affected individuals may also have spinal deformities.
Patients with SMA type 4 may have mild to moderate muscle weakness. They may have skeletal abnormalities, including ankylosis of the mandible. Some affected children may also be unable to sit independently. In addition, some will have a scoliotic spine.
For adults with SMA, treatment includes the use of a medicine called risdiplam. This medication is used to increase the amount of protein produced by the SMN2 gene. The medicine is given over a two-month period. It has been approved by the FDA to treat SMA. It is injected into the space near the spinal canal.
For infants with SMA type 0/1, treatment includes respiratory support. This is because breathing difficulties can lead to restrictive lung diseases. It is important to diagnose the disease before it becomes too severe. The earliest symptom of SMA is diaphragmatic paralysis, which can be seen on chest radiographs.
Other treatments for SMA are being tested in clinical trials. These include medications that can improve muscle function and reduce the severity of symptoms. These drugs have been shown to be safe.
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